The invention relates to apparatus for optimizing the performance of internal combustion engines equipped with a carburetor and particularly for selecting the optimum main jet or nozzle for a carburetor.
The selection of the nozzles or jets for a carburetor used with an internal combustion engine has a marked impact on the performance of the engine. More specifically, the fuel economy, top speed and the vehicle acceleration are markedly influenced by the nozzle selection. The conventional carburetor does not vary fuel delivered to the engine when the air density changes.
A reciprocating internal combustion engine draws the same volume of air during the intake stroke despite the ambient conditions. The weight and density of the air drawn into the cylinder will vary substantially with atmospheric pressure and temperature.
Relative air density gauges have been employed with various engines. One common application is in the stock car racing field although the apparatus is also commonly used for sprint cars, snowmobiles, go carts, and motorcycles. A typical relative air density gauge has a small bellows with air sealed inside the bellows. An increase in air pressure compresses the bellows which is coupled to a needle that is mounted for rotation. Higher atmospheric pressure compresses the bellow and causes the movement of the needle to a higher level on an arcuate scale. Lower atmospheric pressure allows the bellows to expand and causes the needle coupled to the to the bellows to move to a lower position on an arcuate scale. Similarly, cooling of the ambient air cools the air in the bellows and this causes the bellows to contract which results in a higher indication on the scale by the needle. Heating of the ambient air causes the heating of the air within the bellows and this causes the bellows to expand which results in a lower indication on the scale by the needle.
Those skilled in the art will recognize that if the density of the air increases and the quantity of fuel supplied to the engine is constant, the mixture will be lean. This will cause a power loss and could damage the engine. Addition of the optimum amount of fuel, by using a larger jet or nozzle results in a power increase and less risk of engine damage.
The utilization of the air density gauge involves a calculation or trial and error to optimize the jet or jets for the carburetor. Many people are not comfortable with making a mathematical calculation to determine the correct jet size.
It is an object of the invention to provide a construction that will enable even mathematically unsophisticated users to more precisely determine the correct jet or nozzle size.
It is an object of the invention to provide apparatus that will physically cooperate with an associated relative air density gauge.
It is an object of the invention to provide apparatus which is inexpensive to manufacture.
Still another object of the invention is to provide apparatus that may be mounted in a manner that will facilitate use of the apparatus.